Paul Kurtz obituary

Prominent American sceptic who targeted bogus science, religious beliefs and the paranormal

Paul Kurtz was dismayed that the US seems to be more in thrall to spiritual excesses than at any other time, with belief in faith healing, astrology, reincarnation and creationism on the rise Photograph: Don Heupel/AP

Paul Kurtz, who has died aged 86, was one of America's most prominent and persistent sceptics, targeting religious beliefs as well as the claims of bogus science and the para normal. However, after decades of devotion to his cause, he was forced to acknowledge that his nation had become more in thrall to spiritual excesses than at any time he could remember. The public's embrace of religions and belief in God had soared.

Psychic "channellers" proliferated; television ran features hardly questioning dubious religious claims (such as a CBS programme in 1993 about the "discovery" of a piece of Noah's Ark – which turned out to be the result of a hoax); "angels" were pictured on news magazine covers; creationism thrived; millions practised the "power of prayer"; and no career politician dared admit to being a non-believer. Belief in faith healing, astrology, reincarnation and fortune-telling had all risen.

Kurtz reflected in 2000: "It is frightening that what was once considered fringe thinking has now entered mainstream thought." The reason, he speculated in the magazine he founded and edited, Free Inquiry, was that the "frenzy" of US culture and daily life had caused people to latch on to religious and paranormal views as a compensation for their chaotic lives.

Although often labelled an atheist, Kurtz wrote in Multi-Secularism: A New Agenda (2010) that he considered "a sceptic about religious claims" to be a more appropriate term because "it emphasises inquiry. The concept of inquiry contains an important constructive component, for inquiry leads to scientific wisdom – human understanding of our place in the cosmos and the ever-increasing fund of human knowledge."

He believed that the sceptical inquirer is dubious of five claims regarding religion: "1. that God exists; 2. that he is a person; 3. that our ultimate moral principles are derived from God; 4. that faith in God will provide eternal salvation; and 5. that one cannot be good without belief in God."

Kurtz exposed dozens of fraudulent healers, tricksters, shamans and mystagogues through the Committee for the Scientific Investigation of Claims of the Paranormal (later known as the Committee for Skeptical Inquiry), which he founded in 1976. His most successful achievement was probably the formation in 1969 of Prometheus Books, a publishing house devoted to scientific-rationalistic thinking and the foremost of its kind in the world. Named after the Greek mythological figure who mocked the gods, it published many of Kurtz's own works.

Free Inquiry was published by another of his creations, the Council for Secular Humanism, based in Amherst, New York. Into old age, Kurtz travelled to international conferences, wrote editorials, appeared on television and published prolifically (a total of more than 40 books). Throughout all of this he fended off several lawsuits and received daily batches of abusive letters. These came mainly from those describing themselves as Christians, although Kurtz was equally sceptical of Judaism and Islam. After the attacks on New York and Washington on 11 September 2001, he wrote in Free Inquiry: "Unfortunately, the basic tenets of Islam can be interpreted to support terrorism."

Although brought up by non-believer middle-class parents in Newark, New Jersey, where he was born, Kurtz emphasised that on matters such as extrasensory perception and even UFOs he had an open mind until well into adulthood, when the evidence persuaded him otherwise. After high school he fought on the western front as a sergeant in the second world war and then studied at a college in Shrivenham (then in Berkshire and now in Oxfordshire).

Returning to the US, he graduated from New York University in 1948 and then attended Columbia University for a master's and his PhD in philosophy, which he obtained in 1952. His dissertation was entitled The Problems of Value Theory. He taught philosophy at Trinity College in Hartford, Connecticut, a conservative institution, from 1952 to 1959, then at Union College, New York, from 1961 to 1965.

In 1960 he married Claudine Vial, with whom he had four children. A fluent French speaker, Kurtz became visiting professor for one year at Besançon University, in France, in 1965. Then from that year until his retirement as professor emeritus in 1991 he taught at the State University of New York at Buffalo.

The better known of his books were The New Scepticism: Inquiry and Reliable Knowledge (1992), The Courage to Become: The Virtues of Humanism (1997), Skeptical Odysseys: Personal Accounts by the World's Leading Paranormal Inquirers (2001), which he edited, and Skepticism and Humanism: The New Paradigm (also 2001).

He is survived by Claudine; his daughters, Valerie, Patricia and Anne, and son, Jonathan; and five grandchildren.

•Paul Winter Kurtz, philosopher and publisher, born 21 December 1925; died 20 October 2012